Borussia Dortmund need victories not only to make up ground on those above them in the Bundesliga, but also to rebuild their fragile confidence, says Niko Kovac.

Dortmund welcome Union Berlin to the Westfalenstadion on Saturday, having lost both of their domestic games under Kovac, who took over in late January.

BVB, who made the Champions League final last season and will face Lille in the last 16 this term, are 11th in the Bundesliga, eight points adrift of fourth-placed RB Leipzig.

But Kovac does not believe their hopes of qualifying for the next edition of Europe's premier club competition are over.

"We are not too far behind," Kovac said at Friday's pre-match press conference. 

"We have to win the game tomorrow because we need the three points not only to climb up the table but more for us, for the team, for the confidence to feel that we can win games again."

The coach insists they have made progress in training and team meetings, and he feels it is inevitable that their results will turn.

While Dortmund eased into the Champions League's last 16 with a 3-0 aggregate win over Sporting CP, they have struggled in the Bundesliga, with one win in their last seven matches.

"We expect Union will be a very aggressive game," Kovac said. "We play at home and we have to show that we want to win the game.

"We want to win games. We want to be winners. That is why we are here. We know the situation and it is not easy but there is no reason to paint everything black now. 

"I believe that after the rain, comes the sun."